This invention relates to a new package and a process for preparing the new package.
Skin packaging is a cheap, effective way of packaging a whole variety of goods, in particular where immediate point of sale is required. The packaging is convenient, relatively low in cost and typically tamper-proof, since in most cases it is immediately evident if the product has been tampered with. Many self-service stores such as supermarkets use this type of packaging to great extent.
Skin packaging involves the heating of a film to the point at which the surface of the film becomes hot and malleable. The heated film is drawn over an article to be contained, which rests on a board which is often coated with a heat sealable lacquer or varnish. Beneath the board air is drawn through its fibres, causing the heated malleable film sitting on the board to be pulled under pressure, forming a tight skin bonded to the surface above. The film, through heat and film distortion, is pulled over the article. Depending on the shape and size of the article, the film follows the contours of the article, causing a semi-rigid encapsulation of the article. This state is very desirable when packaging awkwardly shaped articles, for example screws, nuts and bolts. The product is thus held firmly in place.
A problem with known skin packages is that they cannot be readily disposed of. The skin film used is predominately made from xe2x80x9cSurlynxe2x80x9d resin, a registered trade mark, which comprises an ionomer (ionomers are copolymers of ethylene and methacrylic acid which have been ionically cross-linked). Such films may not be readily recycled. For example a discarded package comprising xe2x80x9cSurlynxe2x80x9d film may not be easily re-pulped.
In one aspect, the invention seeks to provide a package which can be recycled.
In another aspect the invention seeks to provide a package which is not static, for example it does not attract dust.
Thus the invention provides a package comprising a backing material having a first surface and a film of water soluble or water dispersible material having a sealing surface, portions of the first surface of the backing material and said sealing surface of said film being sealed with at least one article enclosed therebetween, characterised in that the backing material comprises a porous board.
Preferably the backing material is substantially planar. In particular the backing material preferably comprises a chipboard or, more preferably, cardboard. It will be understood that the surface of the board may be pre-treated to avoid undue absorption of adhesive, where present.
Suitable water soluble or dispersible materials include polyethylene oxide; more preferably a polyvinyl alcohol film is used. Such a polyvinyl alcohol film may be a partially or fully hydrolysed or alcoholised erg. 40-99% preferably 70-92% hydrolysed or alcoholised, polyvinyl alcohol film. The polyvinyl alcohol film may in fact be a co-polymer, with a second polymer replacing residual polyvinyl actetate. The film may be a cast film or, more preferably, a blown or extruded film.
The polyvinyl alcohol film may be unoriented, mono-axially oriented or bi-axially oriented. The film may be hot water soluble (e.g. it dissolves in water at a temperature from 40 to 100xc2x0 C., preferably 40 to 50xc2x0 C.) or preferably cold water soluble.
The water soluble or dispersible material may be monolayered or in the form of a laminate, generally of two layers of different or preferably the same material. Typically the laminates will consist of two layers of thickness from 10 to 500 microns.
The film water soluble or water dispersible material which is sealed to the coating is typically of a thickness from 10 to 500 microns, preferably 20 to 150 microns, although it will be understood that the thickness will vary according to the article to be packaged and the film used.
The first surface of the backing layer and the sealing surface of the film may be sealed together in a number of ways. One preferred method is by forming a heat seal between the first surface of the backing material and the sealing surface of the film. Where this is the method, the first surface of the backing material must comprise a heat scalable material, e.g. polyvinyl alcohol or a paper material.
In another preferred aspect at least one of the first surface of the backing layer and the sealing surface of the film is coated with an adhesive, and portions of the first surface of the backing material are sealed to portions of the sealing surface of the film.
The adhesive coating preferably has a thickness from 1 to 10 microns, preferably from 1 to 5 microns.
The adhesive is preferably a thermally activated adhesive, water soluble or water dispersible adhesives being particularly preferred. In general the adhesive comprises a polymer. The adhesive preferably comprises polyethylene oxide or polyvinyl alcohol, polyvinyl alcohol being preferred. It is also preferred that the adhesive comprises the same material as the water soluble or dispersible material having the sealing surface, since they will be thermally active within the same temperature range as each other. Where the adhesive is thermally activated and comprises a different material from the water soluble or dispersible material having the sealing surface, preferably the film becomes malleable in the temperature range at which the adhesive is thermally activated.
Where the article to be packaged is inert to the adhesive, the adhesive may be provided on the film. This may be used for example where the article to be packaged is to be held in place and the adhesive and film may be readily peeled away from the surface of the article, for example metallic objects.
In a further preferred embodiment the backing material is provided with a region uncoated with adhesive between the article and the perimeter of the backing material, preferably running from where the package is to be opened (for example running from a pull tab). This offers advantages to the purchaser of the package, for example when releasing the contents of the package, by making the film more easy to peel.
According to a further feature of the present invention there is provided a process for the preparation of a package according to the invention comprising placing at least one article to be packaged on the first surface of a backing material, positioning a film of water soluble or water dispersible material over the first surface of the backing material, and sealing portions of the film to portions of the first surface of the backing material.
Generally the film is heated before being sealed to the surface of the backing material. Preferably the film is thermoformed before being sealed to the first surface of the backing material, typically at a temperature from 100 to 120xc2x0 C. The backing material is generally placed under suction to draw the film to the surface, and for this reason the backing material may be provided with perforations to increase the suction.
In a preferred embodiment sealing may be accomplished using an adhesive, most preferably a water soluble or water dispersible adhesive. The adhesive is applied to at least one of the sealing layers of the film and the first surface of the backing material. The backing material is preferably coated with the adhesive prior to being sealed to the film.
The coating of water soluble or water dispersible adhesive is preferably applied to the backing material by a gravure process.
In another preferred embodiment, the sealing may be accomplished using a heat seal. A preferred way of providing the heat seal involves using a heated platten moving vertically and squeezing the surfaces to be sealed together under constant pressure and heat sealing around the perimeter of the article on the backing material. The dwell time of the platten in contact with the sealing surfaces will vary according to type of materials used and their thickness. Where the film is polyvinyl alcohol, the sealing temperature range is generally from 120 to 200xc2x0 C., more preferably from 150 to 175xc2x0 C.; and the dwell time is from 0.1 to 5 seconds, preferably from 0.5 to 1 second.
The package of the invention may be used to contain many different types of article. Some typical examples can be found in the packaging of automotive spares and spare parts and fittings across industry segments. Skin packaging of electronic circuit boards and electronic components sensitive to electrostatic discharge. This allows visual identification of components in handling without the risk of damage to the component. Since the packaging is recyclable, the invention could be used to hold powder type chemicals for concrete additives, the packaging of explosive components, the packaging of military ammunition to prevent corrosion, to resolve static problems and to permit easy disposal of the packaging, as both components of the skin packaging are pulpable. It is also well suited to packaging solid detergent chemicals, for example toilet disinfectants.
The following non-limiting example illustrates the invention. The following trade marks appear in the Example: Ad coat, Solublon, Vinex.